From: pgaikwad@nvidia•com (Prashant Gaikwad)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 1/3] ARM: add cpufreq transiton notifier to adjust loops_per_jiffy for smp
Date: Tue, 11 Sep 2012 17:29:05 +0530 [thread overview]
Message-ID: <504F2789.1070006@nvidia.com> (raw)
In-Reply-To: <504E20BE.8050107@wwwdotorg.org>
On Monday 10 September 2012 10:47 PM, Stephen Warren wrote:
> On 09/09/2012 07:17 PM, Shawn Guo wrote:
>> On Fri, Sep 07, 2012 at 10:55:00AM -0600, Stephen Warren wrote:
>>> Yes, that does solve the problem (well, with s/late_init/late_initcall/).
>>>
>>> As you imply, that change wouldn't help if cpu-tegra.c was built as a
>>> module.
>> I doubt that. Have you confirmed it with testing? When you install
>> module cpu-tegra, the pcie initialization has been done, right?
> Never mind, the code can't be built as a module anyway.
>
> Aside from that, I misinterpreted your test patch, and thought that it
> was moving the Tegra cpufreq driver initialization earlier, but it's
> actually moving it later, and in fact by chance after PCIe
> initialization, which explains why it solves the issue.
>
> I think the root of the problem is that cpufreq is lowering the CPU
> frequency, yet the patch which converted Tegra to the common clock
> framework removed the code that actually changes the CPU clock rate. So,
> cpufreq thinks the CPU is running at e.g. 216MHz, but it's actually
> still running at 1.0GHz, and hence re-calculating the delay loops breaks
> things, since delays aren't as long as the system thinks they are. The
> variability is due to whether lowering the CPU frequency just happens to
> occur before or after the PCIe controller is initialized.
>
> Prashant, are you able to fix the clock driver deficiency within the
> next 2-3 days or so (so I can include the fix in the pull requests I
> send for 3.7, which need to be sent before the end of the week)? Or, do
> we need to disable cpufreq for Tegra because of this?
Your fix looks good to me except the concern I have mentioned in reply to that patch.
next prev parent reply other threads:[~2012-09-11 11:59 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-10 5:37 [PATCH v3 0/3] Add a generic cpufreq-cpu0 driver Shawn Guo
2012-08-10 5:37 ` [PATCH v3 1/3] ARM: add cpufreq transiton notifier to adjust loops_per_jiffy for smp Shawn Guo
2012-09-04 23:27 ` Rafael J. Wysocki
2012-09-06 22:35 ` Stephen Warren
2012-09-07 2:58 ` Shawn Guo
2012-09-07 16:55 ` Stephen Warren
2012-09-10 1:17 ` Shawn Guo
2012-09-10 17:17 ` Stephen Warren
2012-09-11 11:59 ` Prashant Gaikwad [this message]
2012-09-11 15:16 ` Stephen Warren
2012-08-10 5:37 ` [PATCH v3 2/3] PM / OPP: Initialize OPP table from device tree Shawn Guo
2012-08-16 21:05 ` Rafael J. Wysocki
2012-08-17 0:52 ` Shawn Guo
2012-08-17 1:53 ` Rob Herring
2012-09-04 23:27 ` Rafael J. Wysocki
2012-08-10 5:37 ` [PATCH v3 3/3] cpufreq: Add a generic cpufreq-cpu0 driver Shawn Guo
2012-09-04 23:18 ` Rafael J. Wysocki
2012-09-05 1:12 ` Shawn Guo
2012-09-05 4:53 ` AnilKumar, Chimata
2012-09-05 5:02 ` Shilimkar, Santosh
2012-09-05 13:38 ` Rafael J. Wysocki
2012-09-05 13:59 ` Shawn Guo
2012-09-05 20:18 ` Rafael J. Wysocki
2012-09-06 7:29 ` Shawn Guo
2012-09-06 19:59 ` Rafael J. Wysocki
2012-08-31 6:42 ` [PATCH v3 0/3] " Shawn Guo
2012-09-01 5:53 ` Rafael J. Wysocki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=504F2789.1070006@nvidia.com \
--to=pgaikwad@nvidia$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox